NAPA, Calif. — A large earthquake caused significant damage and left three critically injured in California’s northern Bay Area early Sunday, igniting fires, sending at least 87 people to a hospital, knocking out power to tens of thousands and sending residents running out of their homes in the darkness.

Two adults and one child have critical injuries and Queen of the Valley hospital has treated 87 people, the city of Napa in California wine country said in a statement Sunday. Most patients have cuts, bumps, bruises, said Vanessa DeGier, spokeswoman for the hospital in Napa. She says the facility has treated a hip fracture and heart attack, but it’s unclear if it was related to the 6.0-magnitude earthquake. The hospital has set up a triage tent and many people are still coming in, DeGier said.

The quake caused six significant fires, including at a mobile home part, Napa Division Fire Chief Darren Drake said. Four mobile homes have been destroyed and two others damaged, the city said. Several other smaller fires have been reported and firefighting efforts have been complicated by broken water mains.

The earthquake struck just before 3:30 a.m. about 4 miles northwest of American Canyon, which is about 6 miles southwest of Napa, said Leslie Gordon of the U.S. Geological Survey said. It’s the largest earthquake to shake the Bay Area since the 6.9-magnitude Loma Prieta quake in 1989, the USGS said. That earthquake struck the San Francisco Bay Area on Oct. 17, 1989 during a World Series game between the San Francisco Giants and the Oakland Athletics, collapsing part of the Bay Bridge roadway and killing more than 60 people, most when an Oakland freeway fell.

NAPA, CA – AUGUST 24: A passerby stops to look at a collapsed carport following a 6.0 earthquake on August 24, 2014 in Napa, California. A 6.0 earthquake rocked the San Francisco Bay Area shortly after 3:00 am on Sunday morning causing damage to buildings and sending at least 70 people to a hospital with non-life threatening injuries. (Photo by Justin Sullivan/Getty Images)

“There’s collapses, fires,” said Napa Fire Capt. Doug Bridewell, standing in front of large pieces of masonry that broke loose from a turn of the century office building where a fire had just been extinguished. “That’s the worst shaking I’ve ever been in.”

Bridewell, who said he had to climb over fallen furniture in his own home to check on his family before reporting to duty, said he was starting to see more reports of injuries.

Three historic buildings in Napa have been damaged, including the county courthouse, and at least two downtown commercial buildings have been severely damaged. A Red Cross evacuation centre has been set up at a high school and crews are assessing damage to homes.

The shaking emptied cabinets in homes and store shelves, set off car alarms and had residents of neighbouring Sonoma County running out of their houses and talking about damage inside their homes. Officials say widespread power outages have been reported in the area.

“It was a rolling quake, said Oakland resident Rich Lieberman. “It started very much like a rolling sensation and just got progressively worse in terms of length. Not so much in terms of shaking, but it did shake. It felt like a side-to-side kind of rolling sensation. Nothing violent but extremely lengthy and extremely active.”

Damage is seen to the Facade of a building housing the Carpe Diem restaurant in downtown Napa, California on August 24, 2014. California’s governor declared a state of emergency Sunday following a strong 6.0-magnitude earthquake that seriously injured three people including a child and ignited fires in the scenic Napa valley wine region. The US Geological Service said that the quake was the most powerful to hit the San Francisco Bay area since the 1989 6.9-magnitude Loma Prieta earthquake. AFP PHOTO / Glen CHAPMANGLEN CHAPMAN/AFP/Getty Images

The USGS says the depth of the earthquake was just less than seven miles, and numerous small aftershocks have occurred in the Napa wine country.

“A quake of that size in a populated area is of course widely felt throughout that region,” said Randy Baldwin, a geophysicist with the U.S. Geological Survey in Golden, Colorado. “The 6.0 is a sizeable quake for this area. It’s a shallow quake. It’s about 6 miles deep. We received hundreds of reports on our website from people that felt it in the surrounding area.”

California Highway Patrol Officer Kevin Bartlett said cracks and damage to pavement closed the westbound Interstate 80 connector to westbound State Route 37 in Vallejo and westbound State Route 37 at the Sonoma off ramp. He says there haven’t been reports of injuries or people stranded in their cars, but there are numerous flat tires from motorists driving over damaged roads.

Highway Patrol and the California Department of Transportation was checking roadways for damage, Bartlett said.

A carport is seen collapsed onto vehicles Sunday, Aug. 24, 2014, in Napa, Calif. Officials say an earthquake with a preliminary magnitude of 6.0 has been reported in California’s northern San Francisco Bay area. (AP Photo/Ben Margot)

California Highway Patrol Officer Daniel Hill told KTVU-TV that road damage appears confined to the Napa and Sonoma areas. He said there appears to be no damage to major bridges in the Bay Area.

In Napa, city spokesman Barry Martin there has been significant damage. Store windows were broken and water mains broke in several locations, one of which left at least one street flooded. Gas breaks have also been reported in several areas. Power outages left streetlights dark.

Numerous emergency vehicles were on the roads in Napa and Sonoma counties.

Comments from Twitter as the West Coast learns of a magnitude 6rumbler in the Bay Area.